The present invention relates to a reamer tip including main and auxiliary cutting edges and a flank, which is provided in the region of the main and auxiliary cutting edges and has an inclined flank region with a back angle of about 7.degree..
As known, reamers having tips of the above-described type serve for finish machining bore surfaces to obtain a very precise bore geometry, together with a high quality bore surface. The reamers of the above-described type usually have two guides, with the tip being secured in a groove provided in a reamer circumference. The main and auxiliary cutting edges, which engage the bore wall, project somewhat further from the outer surface of the reamer than outer surfaces of the guides. This arrangement is designed to prevent action of high pressure forces on the outer surfaces of the guides, so that they would not damage the machined bore wall but would still insure an optimal guidance of the reamer in the bore.
It is well known that, during machining of a bore surface, the tip is subjected to so-called initial wear when the ream is first inserted into the machined bore, and that the initial wear is significantly higher than the subsequent wear. Therefore, it becomes necessary to adjust the projection of the tip from the reamer circumference after a certain time in order to compensate for the initial wear and to obtain the predetermined bore size.
During the first machining of a bore surface, the tip extends further away from the reamer circumference than the guide outer surfaces, and further than after the initial wear of the cutting edges. This results in a relatively non-uniform guidance of the reamer in the machined bore, so that the geometrical characteristics, e.g., the roundness and the surface quality of the bore do not meet the predetermined requirements. Because of the large initial wear, particularly high bore characteristics are difficult to obtain and a complicated adjustment of the operational diameter of a reamer is required. That leads to increased costs of production.
Accordingly, the object of the invention is to provide a reamer tip that would permit to eliminate the above-listed drawbacks and, in particular, would reduce the initial wear to that which takes place later.